Because background checks would disproportionally hurt Obama’s base.

JEFFERSON CITY, Mo. (AP) — Missouri Gov. Jay Nixon vetoed legislation Monday that would have limited who could work in the state as a health insurance guide and blamed a national conservative group for injecting an error into the model legislation.

The vetoed bill would have required criminal background checks for people applying for state licenses as enrollment aides for a federally run health insurance website. Anyone with past convictions involving fraud or dishonesty would have been barred from the jobs.

Missouri is one of more than a dozen Republican-controlled state legislatures that have passed measures tightening requirements for the workers known as navigators or counselors under President Barack Obama’s health care law. While the federal government does not require criminal background checks for navigators, states can set their own rules.

The vetoed Missouri measure mirrored model legislation produced by the American Legislative Exchange Council, an organization of conservative lawmakers and businesses that has opposed Obama’s health care law.